This invention relates to power conversion packaging.
U.S. Pat. No. 6,031,726, issued Feb. 29, 2000, and incorporated by reference, shows a packaging arrangement for a small, high-power-density power converter in which a primary-side converter piece and a secondary-side converter piece mate to form the converter. The two pieces house populated circuit boards in an encapsulant. Each of the circuit boards supports one winding of a main power conversion transformer, and a hole in the encapsulant passes through the center of the winding. After the two pieces are mated, two u-shaped core pieces are inserted through the holes to complete the transformer. At the bottom of the converter, lead frames carry signals and power from the encapsulated circuit boards"" terminals at the ends of the converter. A heat-sink sleeve slips over the assembly to complete the converter. The finished converter is mounted on an external circuit board with the terminals soldered to conductive runs on the surface of the board and a portion of the body lying in a rectangular hole in the circuit board for efficient use of space.
In general, in one aspect, the invention features a power converter that includes a housing, heat generating circuitry in the housing, and a heat conducting metal sheath on the outside of the housing. The housing has an elongated-box shape including two relatively smaller ends and four relatively larger sides, and a heat-conducting metal sheath on the outside of the housing, The heat conducting sheath covers substantially all of the four relatively larger sides.
Implementations of the invention may include one or more of the following features. The metal sheath may be a longitudinally extruded piece that includes fins that run along the length of the box shape. The metal sheath may include two pieces, one of the pieces covering substantially all of three of the relatively larger sides, the other of the pieces covering substantially all of the fourth of the relatively larger sides. At least a portion of the sheath may include a solderable metal surface. Terminals may project from at least one of the smaller ends and be configured to be soldered to conductive runs on a surface of a printed circuit board. The heat conducting metal sheath may have a solderable surface configured and oriented to be soldered to the surface of the printed circuit board when the terminals are soldered to the conductive runs. The other of the pieces may form one of the four relatively larger sides of the housing. The one piece may include three separate sub-pieces that are respectively mounted on each of three of the larger sides.
In general, in another aspect, the invention features an assembly that includes a circuit board having an aperture and a power converter in the shape of an elongated box. The power converter is mounted on the circuit board with a portion of the power converter lying in the aperture. The power converter has a heat sink that surrounds four longer sides of the elongated box and terminals that project from ends of the power converter and are soldered to conductive runs on the surface of the circuit board. There are heat conductive connections between portions of the heat sink and the circuit board.
In general, in another aspect of the invention, a series of power converters are made on a manufacturing line, each of the power converters including a heat sink selected from among a set of different kinds of heat sinks and a core converter. The manufacturing line is configured to enable lot-of-one mixing of power converters in which each power converter in the series may have a different one of the available heat sinks.
Implementations of the invention may include one or more of the following features. The different kinds of heat sinks may differ at least in their capacities for sinking heat, or in their sizes. The core converters of all of the power converters may be the same. The core converters of at least some of the power converters may be selected from among different available kinds of converters.
In general, in another aspect the invention features a power converter having a box-shaped housing having two ends and four sides and heat-generating electronic circuitry held in the housing. Heat-conducting metal shields span substantially all of two opposing sides of the housing. A mounting mechanism attaches the converter to a circuit board in a position in which one of the heat conducting metal shields lies to one side of the circuit board and the other metal shield lies to the other side of the circuit board.
In general, in another aspect, the invention features a method comprising providing an external heat sinking surface on a power converter, and connecting the heat sinking surface to a substrate external to the power converter.
Implementations of the invention may include one or more of the following features. The substrate may include a printed circuit board. The heat sinking surface may be connected to the substrate by soldering or by thermally conductive adhesive. The heat sink may be plated with nickel. The substrate may include a printed circuit board having a conductive pattern on its surface and the heat sinking surface may be soldered to the conductive pattern.
Other advantages and features of the invention will become apparent from the following description and from the claims.